A note on the large-angle anisotropies in the WMAP cut-sky maps

Abstract

Recent analyses of the WMAP data seem to indicate the possible presence of large-angle anisotropy in the Universe. If confirmed, these can have important consequences for our understanding of the Universe. A number of attempts have recently been made to establish the reality and nature of such anisotropies in the CMB data. Among these is a directional indicator recently proposed by the authors. A distinctive feature of this indicator is that it can be used to generate a sky map of the large-scale anisotropies of the CMB maps. Applying this indicator to full-sky temperature maps we found a statistically significant preferred direction. The full-sky maps used in these analyses are known to have residual foreground contamination as well as complicated noise properties. Thus, here we performed the same analysis for a map where regions with high foreground contamination were removed. We find that the main feature of the full-sky analysis, namely the presence of a significant axis of asymmetry, is robust with respect to this masking procedure. Other subtler anomalies of the full-sky are on the other hand no longer present.

10 pages, 3 figeres. We performed a similar analysis of arXiv:astro-ph/0511666 by considering the LILC map with a Kp2 sky cut, and find that the presence of a significant axis of asymmetry is robust with respect to this masking procedure

References in corpus (52)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Angular Power Spectrum
• Asymmetries in the CMB anisotropy field
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Tests of Gaussianity
• A high resolution foreground cleaned CMB map from WMAP
• The significance of the largest scale CMB fluctuations in WMAP
• The Microwave Anisotropy Probe (MAP) Mission
• Detection of non-Gaussianity in the WMAP 1-year data using spherical wavelets
• The axis of evil
• Is the low-l microwave background cosmic?
• Cosmic Topology
• Dodecahedral space topology as an explanation for weak wide-angle temperature correlations in the cosmic microwave background
• Testing the cosmological principle of isotropy: local power spectrum estimates of the WMAP data
• Multipole Vectors--a new representation of the CMB sky and evidence for statistical anisotropy or non-Gaussianity at 2<=l<=8
• On the large-angle anomalies of the microwave sky
• On Foreground Removal from the Wilkinson Microwave Anisotropy Probe Data by an Internal Linear Combination Method: Limitations and Implications
• Circles in the Sky: Finding Topology with the Microwave Background Radiation
• Non-Gaussian Signatures in the Temperature Fluctuation Observed by the Wilkinson Microwave Anisotropy Probe
• Topology and the Cosmic Microwave Background
• Asymmetries in the local curvature of the WMAP data
• Non-Gaussianity of the derived maps from the first-year WMAP data
• The Hot and Cold Spots in the WMAP Data are Not Hot and Cold Enough
• Constraints on mode couplings and modulation of the CMB with WMAP data
• The N-point correlation functions of the first-year Wilkinson Microwave Anisotropy Probe sky maps
• Primordial magnetic field and non-Gaussianity of the 1-year Wilkinson Microwave Anisotropy Probe (WMAP) data
• CMB Anisotropy of the Poincare Dodecahedron
• CMB Anisotropy of Spherical Spaces
• Isotropy of the early universe from CMB anisotropies
• CMB Anisotropy in Compact Hyperbolic Universes I: Computing Correlation Functions
• CMB Anisotropy in Compact Hyperbolic Universes II: COBE Maps and Limits
• Detecting Topology in a Nearly Flat Spherical Universe
• Detectability of Cosmic Topology in Almost Flat Universes
• Are Small Hyperbolic Universes Observationally Detectable?
• Spikes in Cosmic Crystallography II: Topological Signature of Compact Flat Universes
• A Topological Signature in Cosmic Topology
• Constraining Cosmological Topology via Highly Luminous X-ray Clusters
• Spikes in Cosmic Crystallography
• Detecting topology in a nearly flat hyperbolic universe
• Limits on the Detectability of Cosmic Topology in Hyperbolic Universes
• What do very nearly flat detectable cosmic topologies look like?
• Cosmic Crystallography with a Pullback
• Constraints on the Detectability of Cosmic Topology from Observational Uncertainties
• Foreground contributions to the Cosmic Microwave Background
• Topological signatures in CMB temperature anisotropy maps
• A Preferred-Direction Statistic for Sky Maps
• A New Crystallographic Method for Detecting Space Topology
• Distinguishing Marks of Simply-connected Universes
• A method to search for topological signatures in the angular distribution of cosmic objects
• Supernovae Constraints on DGP Model and Cosmic Topology
• Supernovae Constraints on Cosmological Density Parameter and Cosmic Topology

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